This is a resubmission of 1 R01 DA020791-01. Prescription drug abuse is among the nation's most important drug problems due to its physical, social and psychiatric consequences. Increases in non-medical use and presumably the consequences of these drugs have been found especially among younger and older adults. NIDA's PA 04-110, Prescription Drug Abuse, is an attempt to stimulate research in this area, and to understand the populations most at risk for abuse and its consequences. While publications have recently focused on the prevalence of this misuse, methodological efforts aimed at assessing the associated problems have been lacking. As the field has moved forward with prevalence studies, the foundation on which these rates have been built requires attention. With our team's years of experience in assessment development and nosological science, we are primed to address this critical need to aid in the interpretation of findings. This team proposes methodological aims among 400 individuals who have used prescription drugs, primarily stimulants, sedatives, or opioids non-medically, such as when they were not prescribed for them, in larger amounts than prescribed, more often than prescribed, or for longer than prescribed. A community based sample of younger and older users will be enrolled. The aims of this proposal are to: 1) Conduct qualitative research on prescription drug users and health professionals to understand contextual factors related to prescription drug (stimulants, sedatives and opioids) misuse and its consequences. The data will inform revisions to the Substance Abuse Module (SAM) and Risk Behavior Assessment (RBA) for the quantitative study. Focus group topics for user groups (n=4) and health professional groups (n=2) will include those salient to the field. An ethnographic sub-study will also be conducted (n=40) to explain the findings of the quantitative study. 2) Evaluate the inter-rater reliability and validity of the SAM questions, criteria, and abuse of and dependence on each category of prescription drugs. Compare the reliability and validity of these drugs to that for other illicit drugs assessed in the SAM. 3) Understand reasons for poor reliability and misunderstood questions through the use of our computerized Discrepancy Interview Protocol (DIP) and Debriefing Interview, to "perfect" assessments. 4) Evaluate nosological issues about prescription drug abuse, and dependence. 5) Share findings with the Missouri Statewide Epidemiology Work Group, the NIDA Community Epidemiology Work Group, and the DSM-V and ICD XI Substance Related Disorders Committees.